1. Technical Field
This invention generally relates to attachments for excavation and construction equipment and particularly to a sizing bucket for an excavator for use in tieing-in pipe, dirt transport, padding, backfill and clean-up requirements.
2. Background Art
When excavating, and particularly when laying and burying pipe or other conduit (collectively “pipe”), building specifications and codes often include particular requirements relating to the size of the fill material used. Early methods of sizing fill material involved screening dirt over a stationary screen or purchasing pre-sized material. These methods, however, were often cumbersome and expensive. In response to the requirements for specific fill material sizes used for the stages of excavation and construction, various equipment has been developed in the industry to increase the efficiency with which fill material is sized and placed.
Many recent excavation sizing equipment designs, however, involve the use of sizing buckets which include additional powered or mechanically operated equipment to size and place the material. The additional equipment was primarily implemented to avoid clogging of a screen by large materials (i.e. use of a vibrator), or to allow the material to be transported between different locations without falling through the screen (i.e. screen cover). One particular example of an excavator bucket with a screen cover may be found in U.S. Pat. No. 5,743,030 to Sirr (issued Apr. 28, 1998). In this reference, for example, a separately operable cover is placed over the bottom of a bucket which has a screen in its bottom surface. Dirt is scooped into the bucket, the dirt is transported to an appropriate location, and the separate cover is removed from the bottom of the bucket to allow the fill material to fall through the screen. The larger materials, or “bones”, are then placed in a discard pile. Additional powered equipment, however, requires additional hook-ups and causes the bucket to be more difficult to operate, more difficult to connect to the excavator, and more likely to have failure due to the moving parts. Vibrators, such as that shown in U.S. Pat. No. 5,493,796 to Ballew et al. (issued Feb. 27, 1996), are also subject to mechanical or power failure. Without the agitation of the dirt over the screen, the larger materials may prevent the smaller materials from falling through. Additionally, through agitation of the bucket by shaking it back and forth, rather than or in addition to using a separately powered agitator, many excavator operators have found that much of the fill material falls around rather than on or in the desired location.
Another aspect of excavation which currently causes inefficiency and added expense, is the requirement that different excavation equipment be used for various stages of the same excavation project. While laying pipe, for example, a pipe is lowered into a trench by an appropriate excavator with a lowering eye. Next, fill material is either sized through a padding machine or pre-sized and transported to the trench by another excavation machine. The trench is then back-filled by an appropriate front-end loader or the like to meet building specifications and codes, or otherwise filled with a differently-sized fill material. The ground is then “cleaned-up.” In excavation, cleaning-up an area of a filled trench may involve such actions as raking the area for dirt and debris, grading and/or sculpting the land, creating roadways, and the like. For each stage of an excavation process, different excavators or attachments for excavators are used. This increases the cost for the project, increases the equipment necessary to complete the job, and extends the time required to complete the job.